A number of technologies have been proposed and, in some cases, implemented to perform a conversion of one or several two dimensional images into one or several stereoscopic three dimensional images. The conversion of two dimensional images into three dimensional images involves creating a pair of stereoscopic images for each three dimensional frame. The stereoscopic images can then be presented to a viewer's left and right eyes using a suitable display device. The image information between respective stereoscopic images differ according to the calculated spatial relationships between the objects in the scene and the viewer of the scene. The difference in the image information enables the viewer to perceive the three dimensional effect.
An example of a conversion technology is described in U.S. Pat. No. 6,477,267 (the '267 patent). In the '267 patent, only selected objects within a given two dimensional image are processed to receive a three dimensional effect in a resulting three dimensional image. In the '267 patent, an object is initially selected for such processing by outlining the object. The selected object is assigned a “depth” value that is representative of the relative distance of the object from the viewer. A lateral displacement of the selected object is performed for each image of a stereoscopic pair of images that depends upon the assigned depth value. Essentially, a “cut-and-paste” operation occurs to create the three dimensional effect. The simple displacement of the object creates a gap or blank region in the object's background. The system disclosed in the '267 patent compensates for the gap by “stretching” the object's background to fill the blank region.
The '267 patent is associated with a number of limitations. Specifically, the stretching operations cause distortion of the object being stretched. The distortion needs to be minimized to reduce visual anomalies. The amount of stretching also corresponds to the disparity or parallax between an object and its background and is a function of their relative distances from the observer. Thus, the relative distances of interacting objects must be kept small.
Another example of a conversion technology is described in U.S. Pat. No. 6,466,205 (the '205 patent). In the '205 patent, a sequence of video frames is processed to select objects and to create “cells” or “mattes” of selected objects that substantially only include information pertaining to their respective objects. A partial occlusion of a selected object by another object in a given frame is addressed by temporally searching through the sequence of video frames to identify other frames in which the same portion of the first object is not occluded. Accordingly, a cell may be created for the full object even though the full object does not appear in any single frame. The advantage of such processing is that gaps or blank regions do not appear when objects are displaced in order to provide a three dimensional effect. Specifically, a portion of the background or other object that would be blank may be filled with graphical information obtained from other frames in the temporal sequence. Accordingly, the rendering of the three dimensional images may occur in an advantageous manner.